Shareholders' Equity - Company's Outstanding and Exercisable Warrants (Detail)	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Class of Warrant or Right [Line Items]
Total Warrants Outstanding	2,177,425
Exerciseable Warrants Outstanding	462,106
Class One [Member]
Class of Warrant or Right [Line Items]
Exercise Price \| $ / shares	$ 3.10
Total Warrants Outstanding	48,387
Expiration Date	Sep. 19, 2022
Class Two [Member]
Class of Warrant or Right [Line Items]
Exercise Price \| $ / shares	$ 3.10
Total Warrants Outstanding	462,106
Exerciseable Warrants Outstanding	462,106
Expiration Date	May 10, 2024
Class Three [Member]
Class of Warrant or Right [Line Items]
Exercise Price \| $ / shares	$ 3.10
Total Warrants Outstanding	602,414
Expiration Date	Jul. 25, 2024
Class Four [Member]
Class of Warrant or Right [Line Items]
Exercise Price \| $ / shares	$ 3.10
Total Warrants Outstanding	1,064,518
Expiration Date	Nov. 08, 2024